The present invention relates to a closure structure for a vacuum specimen collection container, a vacuum specimen collection container incorporating the closure structure, a vacuum specimen collection system and a holder for a vacuum specimen collection device, which are employed in conducting analytical tests of liquid specimens such as blood and urine or gaseous specimens such as expired gas and working atmosphere, and further to a thermoplastic elastomer composition for forming the closure structure.
A typical specimen collected by vacuum specimen collection systems is blood. Accordingly, a vacuum blood collection container, as illustrative of vacuum specimen collection containers, is explained below.
A typical conventional vacuum blood collection system is disclosed in Japanese Patent Laying-open No. 62-227316 (1987). FIG. 18 illustrates a basic construction of such a conventional vacuum blood collection system. FIG. 18(a) shows a vacuum blood collection tube 30 including a blood collection tube 32 sealed at its open end by attachment of a closure structure 31 having good needle hole sealability and gas barrier properties. FIG. 18(b) shows a holder 33 for vacuum blood collection device, into which the vacuum blood collection tube 30 can be inserted. The holder 33 has a blood collection needle retaining bore 34 at its one end. The blood collection needle retaining bore 34 carries an internal thread. FIG. 18(c) shows a vacuum blood collection needle 35 which includes a hub 36 having an external thread and needle tips 37, 38 positioned on opposite sides of the hub. The external thread on the hub 36 is configured to screw into the internal thread on the blood collection needle retaining bore 34 of the holder 33 shown in FIG. 18(b).
FIG. 20 is a perspective view, showing the vacuum blood collection system of FIG. 18 while in use for blood collection. When in use for blood collection, the vacuum blood collection needle 35 is screwed into the blood collection needle retaining bore 34. Then, the vacuum blood collection container 30 is inserted in the holder 33 such that the needle tip 37 of the blood collection needle 35 is forced to penetrate the closure structure 31 to a depth of less than its thickness, whereby the needle tip 37 is kept sealed. This is to prevent the blood from leaking through the needle tip 37 when the needle tip 38 is inserted in a blood vessel.
As shown in FIG. 20, an operator holds a whole assembly of blood collection needle 35, holder 33 and blood collection container 30 in an slanted orientation along an axial direction of blood vessel of a subject and then inserts the exposed needle tip 38 in the blood vessel. When the blood collection container 30 is pushed further inside the holder 33, the needle tip 37 is forced to penetrate through the closure structure 31 and the pressure differential between the blood collection container side and the blood vessel side causes the blood to flow into the blood collection container 30. When the pressure differential decreases to zero, the blood ceases to flow. Then, the whole assembly is drawn from the blood vessel to end the blood collection procedure.
The above-described blood collection needle 35 is a so-called single blood collection needle for use in introducing blood into a single vacuum blood collection container. In distributing blood into plural vacuum blood collection containers, the needle tip must be kept in a position within the blood vessel while one blood collection container is replaced by another. Such use of single blood collection needle possibly leads to the leakage of blood from the needle tip 37. Accordingly, a multiple blood collection needle 39 as shown in FIG. 19 has come into use. The multiple blood collection needle 39 has an elastic sheath 40 which encloses the needle tip 37 for insertion into the closure structure in an airtight manner to prevent blood leakage therefrom. Where such a multiple blood collection needle 39 is used, the blood collection needle 39 assembled to the holder 33 is operated to penetrate in the blood vessel. Subsequently, the blood collection container 30 is assembled to the holder 33 so that it is brought into communication with the blood vessel. This results in collecting the blood in the blood collection container 30.
Key qualities sought for elastic materials used to form the closure structure 31 as shown in FIG. 18(a) include gas barrier properties sufficient to maintain a vacuum pressure within the blood collection container and the ability to seal a needle hole left after the needle tip has been retracted. This has led to the widespread use of crosslinked isobutylene-isoprene rubbers (crosslinked IIR, crosslinked butyl rubber).
The closure structure 31 shown in FIG. 18(a) has a configuration most widely adopted in the art. Subsequent to collection of blood, the closure structure 31 is detached to dispense the blood from the blood collection container 30. It has been reported, however, that the blood is likely caused to splash the moment the closure structure 31 is detached. This is attributed to the configuration of closure structure adopted to provide the improved seal for better maintaining the interior vacuum pressure of the blood collection container 30. In order to obviate such problems, the use of composite structural closures incorporating a cover disposed to cover a crosslinked butyl rubber closure and prevent splashing of blood has been proposed, for example, by Japanese Patent Laying-Open Nos. Hei 5-168611, Hei 4-215961, Sho 59-228831, Sho 60-242367, Sho 61-170437, Sho 59-230539 and Hei 3-505320.
As stated above, crosslinked butyl rubber has been widely used in the manufacture of closure structures. The use of such crosslinked butyl rubber is however reported to accompany problems, such as the requirements to undergo a prolonged vulcanizing period and subject to washing with water to remove elutable contents thereof, resulting in the reduced productivity.
The crosslinked butyl rubber, because of its inability to be chemically or thermally adhered to a cover member, is physically assembled with the cover member. Such a built-in construction however suffers from a problem of easy separation of the closure structure. For the purpose of preventing such separation, a construction has been proposed which utilizes a generally double-walled tubular cover member having an inner tubular portion fittingly embedded into the crosslinked butyl rubber member. However, the excellent sealing performance of the crosslinked butyl rubber closure structure relies not only upon the properties intrinsic to the material but also upon the pressure that is exerted on the closure structure when it is fitted in a blood collection tube and acts to close a hole pierced by a needle. Accordingly, the use of the generally double-walled tubular cover member may result in the reduced needle hole sealability.
Japanese Patent Laying-Open No. Sho 57-59536 proposes a closure structure wherein a superior gas barrier film is adhered to or embedded in an inferior gas barrier closure body formed of thermoplastic elastomer. The requirement to add an adhering or embedding process, however, results in sacrificing the high productivity that is a key advantage obtained with the use of thermoplastic elastomer.
Closure structures which can be injection molded in a highly productive fashion are disclosed, for example, in Japanese Patent Laying-Open Nos. Sho 58-58057, Sho 61-64253 and Sho 59-28965. These references describe the use of thermoplastic resins and elastomers, as injection moldable materials, which incorporate uncrosslinked butyl rubbers or flake-form inorganic fillers to assure increased elasticity and gas barrier properties. However, the loading of such additives results in the reduced needle hole sealability, which necessitates incorporation of another thermoplastic elastomer member into a needle cannula pierceable site, and also to the increased resistance to needle penetration.
In Japanese Patent Laying-Open Nos. Hei 4-279152 and Hei 7-51253, a composite structure is proposed. Injection moldable materials, such as thermoplastic elastomer, are used for the needle-pierceable elastic member. The above-described cover for blocking the blood splash is further provided to cover a closure structure. However, no explicit disclosure is not provided as to the improvement in gas barrier properties of thermoplastic elastomers. Simply following a conventional measure, a separate gas barrier sheet is additionally disposed on an upper face of the cover.
In Japanese Patent Laying-Open Nos. Sho 57-154057, Hei 1-76831 and Hei 2-174835 and Utility Model Laying-Open No. Sho 62-160908, sheet-form closures distinct in configuration from typical rubber closures are proposed. A layered sheet such as consisting of an aluminum foil and a needle hole-sealable rubber sheet or rubber tip is directly joined to an open end of a blood collection container by an adhesive or fusion bonding.
This new type of sheet-form closure is reported to have a superior gas barrier property because of its incorporation of a gas impermeable material such as an aluminum foil. It is also reported to exhibit an extremely low resistance to penetration of a blood collection needle, leading to the marked reduction of blood collecting operation load. The high productivity also results. However, the closure once removed from the open end of the blood collection container can not be rejoined thereto. This necessitates separate preparation of a detachable stopper which, when attached, allows storage of specimen in the blood collection container.
Japanese Patent Laying-Open No. Hei 3-97450 proposes a closure formed from injection moldable thermoplastic resins. The closure has an axially-extending communicating hole that permits a needle cannula to pass therethrough. The hole is filled with a needle-pierceable elastic sealing member. Alternatively, a laminated sealing member consisting of an aluminum foil and a vulcanized rubber sheet is brought into close contact with the hole. The closure is coupled to the blood collection container not by elastic fit commonly adapted for conventional closure structures but by rigid fit between rigid thermoplastic resins. This is reported as being based on the following reason: When the rubber elastic closure is detached from the blood collection tube filled with blood and then reattached, its superior sealability serves such that an air inside the blood collection tube is prevented from escaping therefrom and is compressed to increase its pressure. The counterforce that the increased pressure exerts against the closure tends to push the closure off the blood collection tube. The use of rigid fit obviates this disadvantage.
The reference describes the rigid fit as being also effective in maintaining an internal vacuum pressure of the blood collection tube. However, molding of thermoplastic resins is often accompanied by defects that disturb close contact of the closure with an inside wall of the blood collection tube or by deformation based on residual strain. Accordingly, the rigid fit used to couple the closure to the blood collection tube presents a problem from an aspect of quality control.
Even in cases where any of the above-described closures is used in combination with the multiple blood collection needle 39 to collect blood, the blood collection container is subjected to a counterforce that the elastic sheath 40 disposed to cover the closure penetrating tip of the blood collection needle exerts when it is compressed. A kickback phenomenon which repels the vacuum blood collection tube from the vacuum blood collection device holder 33 is then likely caused to occur.
In order to prevent the kickback phenomenon, it is required to increase sliding friction resistance either between an outer surface of the closure-penetrating needle cannula 37 and a needle penetrating portion of the closure or between an inner wall surface of the holder and an outer surface of the vacuum blood collection tube. However, the former leads inevitably to the increased resistance to needle penetration. For the latter, it becomes necessary to increase sliding friction resistance or engagement retention between the holder and the blood collection tube or between the holder and the outer surface of the closure, as by providing a ridge or a spring-like elastic tongue on an inner wall surface of the holder or providing a fixed or movable hooking mechanism. However, in either case, the increased resistance results when the blood collection tube is inserted in and pulled out from the holder. This obliges an operator to put the increased strength into its finger tip in a forced posture, leading to the increased tendency for the needle tip to move in the blood vessel. As a result, a heavier burden is imposed on both the operator and subject.
Even in the case where the friction resistance or engagement retention between the holder inner wall surface and the blood collection tube outer surface is increased, outer surface portions of the blood collection tubes or the closures must be uniformly expanded to diameters which permit slide or engagement thereof with an inner surface of the holder, since one blood collection device holder is usually designed to accommodate various sizes of blood collection tubes and closures. Small-volume blood collection tubes having sizes of about 4-7 ml have small diameter tubular bodies. Usually, a test tube rack designed to hold such blood collection tubes define spaces sized for accommodating the tubular bodies at small distances. Accordingly, the attempt to accommodate the blood collection tubes locally increased in diameter as described above laterally in a row within such a test tube rack fails since the larger diameter portions of those blood collection tubes interfere with each other. This has actually obliged the use of a larger test tube lack designed to accommodate 10 ml tubes, which provides a loose hold to the blood collection tubes and imposes marked inconveniences.
There accordingly remains a need for closure structure for vacuum blood collection container, which can enjoy high productivity and maintain a vacuum pressure within the blood collection tube and which is excellent in needle cannula-pierceable property, needle hole sealability and kickback preventing property.
An object of the present invention is to provide a detachable closure structure for vacuum specimen collection container, which can enjoy high productivity and maintain a vacuum pressure within the blood collection tube and which is excellent in needle cannula-pierceable property, needle hole sealability and kickback preventing property; a vacuum specimen collection container incorporating the closure structure; vacuum specimen collection device holder and a thermoplastic elastomer composition for formation of the closure structure.
A closure structure for a vacuum specimen collection container, in accordance with a first invention of the present invention is constructed such that it can be detachably fitted in an open end of a specimen collection tube in an airtight manner to maintain a vacuum condition inside the specimen collection tube. Characteristically, it includes a grip section having a tubular side wall portion for providing a finger grip, a partition portion extending inward from the side wall portion and a through-hole through which a specimen collection needle cannula can be passed into the specimen collection tube; a rubber-like elastic needle cannula penetrating portion provided to fill up the through-hole in the grip section and having the capability to be pierced by a needle cannula and reseal a hole if left after the needle cannula is retracted; and a rubber-like elastic fitting portion extending downward from a peripheral edge portion of the rubber-like elastic needle cannula penetrating portion and configured to follow an inner surface profile at the open end of the specimen collection tube so that it can contact fit therein in an airtight fashion. The grip section has a higher rigidity relative to the needle cannula penetrating portion and the fitting portion. Also, the tubular side wall of the grip section is provided on its inner side with at least one raised or recessed portion for kickback preventive purpose.
In a particular aspect of the present invention, the closure structure for a vacuum specimen collection container further includes a fitting portion supporting member which extends from the partition portion toward the fitting portion and is embedded in the fitting portion. This fitting portion supporting member has a lower edge located below a bottom surface of the needle cannula penetrating portion on which a protuberance is provided.
A closure structure for a vacuum specimen collection container, in accordance with a second invention of the present invention, is constructed such that it can be detachably fitted in an open end of a specimen collection tube in an airtight manner to maintain a vacuum condition inside the specimen collection tube. Characteristically, it includes a grip section having a tubular side wall portion for providing a finger grip, a partition portion extending inward from the side wall portion and a through-hole through which a specimen collection needle cannula can be passed into the specimen collection tube; a rubber-like elastic needle cannula penetrating portion provided to fill up the through-hole in the grip section and having the capability to be pierced by a needle cannula and reseal a hole if left after the needle cannula is retracted; and a rubber-like elastic fitting portion extending downward from a peripheral edge portion of the rubber-like elastic needle cannula penetrating portion and configured to follow an inner surface profile at the open end of the specimen collection tube so that it can contact fit therein in an airtight fashion. In particular, the needle cannula penetrating portion has a protuberance on its bottom surface.
For closure structures for a vacuum specimen collection container according to the first and second inventions of the present application, the through-hole is configured to increase its diameter toward an upward direction from the needle cannula penetrating portion.
In accordance with another particular aspect of the present invention, a wall thickness T1 (mm) and an oxygen permeability coefficient P1 (ml/cm2xc2x7mmxe2x88x921xc2x7secxc2x7cmHg) at 25xc2x0 C. of the partition portion in the grip section, a wall thickness T2 (mm) in a needle penetrating direction and an oxygen permeability coefficient P2 (ml/cm2xc2x7mmxe2x88x921xc2x7secxc2x7cmHg) at 25xc2x0 C. of the needle cannula penetrating portion, a minimum cross-sectional area Sd (cm2) of the through-hole in the grip section and an open area So (cm2) at the open end of the specimen collection tube are selected to satisfy the following relationship (1):                                                                         (                                  So                  -                  Sd                                )                            xc3x97              P1                        T1                    +                                    Sd              xc3x97              P2                        T2                          ≦                  10          xc3x97                      10                          -              10                                                          (        1        )            
Preferably, the grip section comprises a thermoplastic resin composition having an oxygen permeability coefficient at 25xc2x0 C., P1, of not exceeding 30xc3x9710xe2x88x9210 ml/cm2xc2x7mmxe2x88x921xc2x7secxc2x7cmHg, the needle cannula penetrating portion comprises a thermoplastic elastomer composition having an oxygen permeability coefficient at 25xc2x0 C., P2, of not exceeding 700xc3x9710xe2x88x9210 ml/cm2xc2x7mmxe2x88x921xc2x7secxc2x7cmHg, and the fitting portion comprises a thermoplastic elastomer composition having an oxygen permeability coefficient at 25xc2x0 C. of not exceeding 10,000xc3x9710xe2x88x9210 ml/cm2xc2x7mmxe2x88x921xc2x7secxc2x7cmHg. Also, a ratio of a minimum cross-sectional area Sd of the through-hole in the grip section to an open area So at the open end of the specimen collection tube, Sd/So is adjusted not to exceed 0.7.
While not limiting the invention, the grip section is comprised principally of at lease one selected from the group consisting of polyester, polyamide, polyallylate, polyacetal and ethylene-vinyl alcohol copolymer, and the needle penetrating portion and the fitting portion are comprised of thermoplastic elastomer that can be chemically or thermally adhered to the grip section.
A vacuum specimen collection container according to the present invention includes a closure structure according to the present invention and a vacuum specimen collection tube.
In accordance with a particular aspect of the present invention, a vacuum specimen collection container includes a closure structure according to the second invention and a vacuum specimen collection tube having a rubber-like elastic, closure structure receiving portion at an inner face of its open end.
A vacuum specimen collection system according to the present invention includes a closure structure for a vacuum specimen collection container according to the present invention, a vacuum specimen collection tube, a tubular holder having an opening at its one end for receiving the vacuum specimen collection tube and a means at its another end for retaining a specimen collection needle cannula, and a vacuum specimen collection needle. Provided deep inside the holder on the needle cannula retaining side is an elastic member which has a recessed or raised portion engageable with the raised or recessed portion on the inner side of the tubular side wall in the grip section of the closure structure.
A holder according to the present invention is the holder for use in combination with a closure structure for a vacuum specimen collection container according to the present invention. The holder is characterized as being tubularly configured to have an opening at its one end for receiving a vacuum specimen collection tube and a means at its another end for retaining a specimen collection needle cannula and as being provided deep inside thereof on the needle cannula retaining side with an elastic member having a recessed or raised portion engageable with the raised or recessed portion on the inner side of the tubular side wall in the grip section of the closure structure.
In accordance with a further aspect of the present invention, a thermoplastic elastomer composition is provided which can be used to form a closure structure for a vacuum specimen collection container according to the present invention. This thermoplastic elastomer composition contains thermoplastic elastomer having rubber elastic domains produced via dynamic crosslinking under a catalyzing action of transition metal oxide, and a compound which can form a water-insoluble salt or chelate with the transition metal.